The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Transmissions are devices well known in the art comprising means to convert torque from one or more spinning shafts into torque on one or more spinning shafts. Transmissions can redirect torque in multiple directions depending upon the transmission configuration. Transmissions can reverse shaft spinning direction, and transmissions can include a gear reduction factor, transforming one shaft speed and torque to another shaft speed and torque by means well known in the art. Transmissions can utilize discrete gear states to accomplish the various torque transmission and conversion functions required. Such transmissions use clutches, brakes or other torque transfer devices (hereafter clutches) to engage and disengage various transmission members in order to shift between gear states. Transmission shifts usually include a disengagement of a first clutch, interrupting the torque delivered through the transmission, and then an engagement of a second clutch, reestablishing the torque delivered through the transmission.
Through transmission shifts, an input torque and shaft speed fixed within a certain range can perform a wide variety of functions. For instance, in a motor vehicle comprising an internal combustion engine, the engine supplies a torque and a shaft speed within a certain range of engine operation. A transmission in a low gear with a high gear reduction ratio can be utilized to launch a vehicle from a stopped position, with the engine shaft speed being reduced by the high gear ratio to an output shaft with a lower shaft speed. However, in the conversion, the torque of the output shaft is significantly higher than the torque of the engine shaft, facilitating a high propelling force needed to move an initially stopped vehicle. As the vehicle begins to move, the output shaft, coupled to the wheels of the vehicle, gains speed. The engine connected through the transmission to the output shaft at a fixed gear ratio can only impart so much speed to the output shaft at the low gear ratio, but by shifting gear state within the transmission to a gear state with a lower gear reduction ratio, the engine shaft can continue to accelerate the output shaft to greater speeds. One having ordinary skill in the art will appreciate that such transmission shifts can be used to up shift and down shift, accomplishing a wide variety of driving functions.
Additionally, a vehicle with a hybrid drive powertrain, comprising two or more potential sources of input torque, for instance an engine and an electric machine receiving energy from an energy storage device such as a battery, can utilize a transmission to transmit torque in various directions between the various components of the hybrid drive powertrain. For instance, an electric machine can operate to receive torque from the transmission to provide energy to the energy storage device, may also impart torque to the transmission to assist in propelling the vehicle.
Transmission shifts are necessary to accomplish the intended functions of the transmission, changing from one gear state to another in order to transmit torque as required. However, as described above, transmission shifts may include an interruption to the torque provided through the transmission. Such an interruption of torque creates an interruption in the function being served by the torque. In a motor vehicle, wherein the output torque can be used to propel or accelerate the vehicle, an interruption to the torque in the output shaft may result in a rapid and perceptible change in acceleration or jerk. Such interruptions in torque and the accompanying changes in acceleration may result in undesirable drivability. Additionally, the engine continues to turn through the interruption in torque, thereby consuming fuel without producing any output torque, and there are additional efficiency losses resulting from a transmission shift associated with engaging and disengaging associated clutches, both resulting in lower overall fuel efficiency for the vehicle.
While transmission shifts are often necessary based upon operation of the vehicle, circumstances can sometimes arise where a transmission shift, may be unnecessary. One instance impacting the necessity of transmission shifts includes an upcoming slowing of the vehicle by the operator.
Electronic means of tracking vehicle position and coordinating vehicle position with geographic, road, traffic, or other information are known in the art. Exemplary accessible electronic means to accomplish such data acquisition includes global position systems (GPS) in coordination with electronic maps, digital map software using means to track the movement of the vehicle, Internet-based wireless-accessible data processing, vehicle to vehicle communications, and vehicle to infrastructure communications and other remote computing resources. Information from such means include, for example: road classification, such as highway, local road, parking lot, gravel road, etc.; speed limits for various stretches of road; traffic conditions for various stretches of road, including real-time evaluations of congestion, signals sent from cooperating vehicles experiencing traffic, analysis of cellular phone patterns in other cars, and predictions based upon likely rush hour traffic or sporting event traffic; road slopes; road curvature; location and status of traffic lights, signals, construction zone markers, speed bumps, or other traffic direction indicators impacting vehicular travel; existence or lack of features likely to impact travel along a certain stretch of road, such as exit ramps or truck weigh stations; and analysis of vehicle or specific operator driving patterns, habits, registered schedules, electronic planner calendars, or other predictive measures. Additionally, likely routes of travel can be estimated based upon, for example, operator entered destinations, computerized analysis of driver habits and patterns.